What does it mean that externalize your progress?

Progress you cannot see is progress you will not sustain. Externalize it or lose it.

Example: You have been studying systems thinking for three months. You feel like you have learned nothing because your internal sense of progress is vague and unreliable. Then you open the document where you have been logging one concept per day with a date stamp. Ninety entries stare back at you. The evidence is unambiguous — you have covered enormous ground. Without that external record, the feeling of stagnation would have won. With it, you have proof that overrides the feeling.

Try this: Choose one area where you are actively trying to improve — a skill, a habit, a project. Create a single document or spreadsheet with three columns: date, what you did, and what changed. Fill in the last seven days from memory (you will notice gaps — that is the point). From today forward, spend sixty seconds at the end of each day adding one row. After two weeks, read the full log top to bottom. Notice how your perception of your own progress shifts when the evidence is external and sequential.